Question

Which of the following is an empty set

• A.
• B.
• C.
• D.

Answer 1

The correct option is B

Since $x^2$ + 1 = 0, gives $x^2=-1$

⇒ $x=\pm i$

∴ $x$ is not real but $x$ has to be is real (given)

∴ No real value of $x$ is possible in this case.